CIHM 
Microfiche 
Series 
(Monographs) 


ICMH 

Collection  de 
microfiches 
(monographies) 


CaoMJian  Instttuto  for  Historical  MIcroraprodiictiora  /  InstHirt  canadiMi  da  m^^ 


Technical  and  Bibliographic  Notes  /  Notes  techniques  et  bibliographiques 


The  Institute  has  attempted  to  obtain  the  best  original 
copy  available  for  filming.  Features  of  this  copy  which 
may  be  bibliographically  unique,  which  may  alter  any  of 
the  images  in  the  reproduction,  or  which  may 
significantly  change  the  usual  method  of  filming  are 
checked  below. 

0  Coloured  covers  / 
Couverture  de  couleur 

0   Covers  damaged  / 
Couverture  endommagie 

□  Covers  restored  and/or  laminated  / 
Couverture  restaur^e  et/ou  pelliculie 

Cover  title  missing  /  Le  litre  de  couverture  manque 

Coloured  maps  /  Cartes  g^raphiques  en  couleur 


Coloured  ink  (i.e.  other  than  blue  or  black)  f 


I I   Encre  de  couleur  (i.e.  autre  que  bleue  ou  noire) 

□  Cotoured  plates  and/or  illustrations  / 
Planches  et/ou  illustrations  en  couleur 


D 
D 
D 


D 


Bound  with  other  material  / 
Relii  avec  d'autres  documents 

Only  editton  available  / 
Seule  ^ditton  disponible 

Tight  tending  may  cause  shadows  or  distortion  atong 
interior  margin  /  La  reliure  serrie  peut  causer  de 
rombre  ou  de  la  distorston  le  long  de  la  marge 
intirieure. 

Blank  leaves  added  during  restorations  may  appear 
within  the  text.  Whenever  possible,  these  have  been 
omitted  from  filming  /  II  se  peut  que  certaines  pages 
blanches  ajout^es  lors  d'une  restauration 
apparaissent  dans  le  texte,  mais,  lorsque  cela  ^tait 
possible,  ces  pages  n'ont  pas  i\i  filmies. 


L'Institut  a  microfilm^  le  meilleur  exemplaire  qu'il  lui  a 
i\6  possible  de  se  procurer.  Les  details  de  eel  exem- 
plaire qui  sont  peut-^tre  uniques  du  point  de  vue  bibii- 
ographique,  qui  peuvent  modifier  une  image  reproduite, 
ou  qui  peuvent  exiger  une  modification  dans  la  m^tho- 
de  normale  de  filmage  sont  indiqu^s  ci-dessous. 

Coloured  pages  /  Pages  de  couleur 

\l/\  Pages  damaged  /  Pages  endommag^es 

□   Pages  restored  and/or  laminated  / 
Pages  restaur^es  et/ou  pellicul^es 

: — >i  Pages  discotoured,  stained  or  foxed  / 
•-    '   Pages  d^colortes,  tachet^es  ou  piqudes 

I     I  Pages  detached  /  Pages  ddtach^esi 

»     ;  Showthrough/ Transparence 


D 
D 
D 


D 


Quality  of  print  varies  / 
Qualit^  in^gale  de  I'impresston 

Includes  supplementary  material  / 
Comprend  du  materiel  suppl^mentaire 

Pages  wholly  or  partially  obscured  by  errata  slips, 
tissues,  etc.,  have  been  refilmed  to  ensure  the  best 
possible  image  /  Les  pages  totalement  ou 
partiellement  obscurcies  par  un  feuitlet  tferrata,  une 
pelure,  etc.,  ont  i\i  filmies  k  nouveau  de  fa(on  k 
obtenir  la  meilleure  image  possible. 

Opposing  pages  with  varying  colouration  or 
discotourattons  are  filnied  twice  to  ensure  the  best 
possible  image  /  Les  pages  s'opposant  ayant  des 
colorations  variables  ou  des  decolorations  sont 
fiim^es  deux  fois  afin  d'obtenir  la  meilleure  image 
possible. 


r~7j   AddHtonal  comments  / 


Commentaires  suppl^mentalres: 


Pagination  Is  as  follows:  p.  219-225. 

La  pagination  est  comme  suit:  p.  219-223. 


This  htm  Is  filmtd  tt  tht  rtdueilen  ratio  chtekid  b«low  / 

Ca  decuRMM  ttt  Ulm4  au  faux  d«  rMuction  indiqu<  ci-dtiteui. 


10x 

14x 

18x 

22x 

26x 

30x 

vy 

12x 


16x 


20x 


24  X 


28x 


32x 


The  copy  filmed  h«r«  has  bean  raproduesd  thanks 
to  th«  sanarosity  of: 


L'oxamplaira  filmi  fut  raproduit  grica  i  la 
g4n*ro«iti  da: 


University  of  Toronto 

Gerstein  Sciences  Information  Centre 

Tha  imcgas  appaaring  hara  ara  tha  baat  quality 
possibia  eensidaring  tha  condition  and  lagibility 
of  tha  original  copy  and  in  liaaping  with  tha 
filming  contract  apacif icationa. 


Original  copiaa  in  printad  papar  covars  ara  fllmad 
beginning  with  ttta  front  covar  and  anding  o;t 
tha  laat  paga  with  a  printad  or  illustratad  impraa* 
•ion,  or  tha  bacii  covar  whan  appropriata.  All 
othar  original  copiaa  ara  filmad  baginning  on  tha 
first  paga  with  a  printad  or  illustratad  impraa* 
sion.  and  anding  on  tha  last  paga  with  a  printad 
or  illuatratad  impression. 


Tha  laat  racordad  frama  on  aach  microfiche 
shall  contain  tha  symbol  >^^  (meaning  "CON- 
TINUED"), or  the  symbol  ▼  (meaning  "END"), 
whichever  applies. 


University  of  Toronto 

Gerstein  Sciences   Information  Centre 
Les  images  suivantas  ont  it*  raproduites  avac  la 
plus  grand  soin.  compts  tenu  de  la  condition  at 
da  la  nattet*  da  rexemplaira  film*,  et  on 
conformit*  avac  lea  conditiona  du  contrat  de 
filmaga. 

Lee  exempleirea  originaux  dont  la  couvertura  9n 
pepier  eet  imprimOe  sent  filmOs  en  eommencant 
par  la  premier  plet  et  en  terminant  soit  par  la 
darni*re  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustretion.  soit  par  la  second 
plat,  seion  le  cas.  Tous  lee  eutres  exempleires 
eriginaux  sent  filmds  «n  commandant  par  la 
premi*re  pege  qui  comporte  une  empreinte 
d'impreasion  ou  d'illustretion  at  en  terminent  par 
la  demi*re  pege  qui  comporte  une  telle 
empreinte. 

Un  des  symboles  suivents  apparattra  sur  la 
derni*re  image  de  cheque  microfiche,  selon  le 
cea:  le  symbols  — ^  signifie  "A  8UIVRE ".  le 
symbols  ▼  signifie  "FIN". 


Maps,  plates,  cherts,  etc..  may  be  filnted  at 
different  reduction  retios.  Those  too  Isrge  to  be 
entirely  included  in  one  exposure  ore  filmed 
beginning  in  the  upper  left  hend  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Lea  cartea,  planchea.  tableaux,  etc..  peuvent  *tre 
film*s  *  des  taux  de  r*duction  diff*rents. 
Lorsque  le  document  est  trop  grand  pour  *tre 
reproduit  en  un  soul  clich*.  il  est  film*  *  partir 
da  Tangle  sup*rieur  gauche,  de  gauche  *  droite. 
et  de  haut  an  bas,  an  prenant  la  nombra 
d'images  n*cessaire.  Lea  diegrammes  suivents 
illustrent  la  mOthoda. 


1  2  3 


1 

2 

3 

4 

S 

e 

3 


1 


d    /"?6-^r-/' 


A  NEW  FORM  OF  SPECTRO-COMPARATOR 


-tr 
"cr 

:nj 

"  T 


KAi.rn  i:  1)1  i.iKV 


\.    ■ 


K.'l>riiilril  i    r  pn.  ilr  .  it.  ill  it  i,im  li..:n 
•r.n     \M«ol•..V^.<ALJuL•K^M,V.■l    \l.Vr,\.     :    <H<tHr..,i 


A  NIAV  FORM  OK  SPI.C  I  K( »  (OMI'AKA  Ink 

»v  KAI.ni   I      DI    l.l  KV 

Hy  finployiiif;  a  half  silvircil  surf.nf  ami  two  niii  rosii)|K'^.  it  i^ 
|w)ssil)li-  for  OIK'  ti>  »onsfni»t  a  toniparatnr  |>i)ss»ssinn  n|M(  i.il 
advantam's  in  thi-  nuasurtiiuiits  and  (uiiiiiari^on^  nf  |>liulii>;rai>li> 
of  spectra.     'I'hc  dtviir  may  l>i-  arranmd  in  srvcr.il  ways: 

I.  Thi'  miirosiopcs  may  1h'  stt  up  with  thi'ir  axes  intiTstt  tiiii; 
on  either  side  of  the  oWjeitives  and  with  the  half  >iivereil  Mirl.ue 
at  the  intersection. 

II.  The  microscopes  may  he  set  up  with  the  axes  of  thi-  ol)jei  - 
lives  parallel.  One  beam  of  lijiht.  after  ])as>in^;  through  it-> 
objective,  is  turned  by  reflection  throuj;h  one  or  two  ri;;ht  anodes 
to  meet,  at  the  half-silvered  surface,  the  direit  or  simii.irly 
reflected  beam  from  the  other  objective. 

The  half-silvered  surface  transmits  and  rellci  ts  in  either  ca^e 
about  half  of  each  beam;  and  tli  imaijes,  side  hy  side  or  over- 
lapping, may  be  observed  in  two  directions  at  ri>;ht  angles  to  one 
another. 

By  emi)loyinK  the  arrangement  I  in  such  form  as  shown  in  the 
diagram,  it  i--  possible  to  produce,  with  a  minimum  of  optit.il 
surfaces,  two  sets  of  images  in  con\enient  positions  for  altern.itc 
measurement,  the  configurations  appearing  rotated  i  So  degrees  with 
respect  to  one  another.  In  the  case  of  sjiectra,  one  eNejiiece  would 
show  "violet  right"  and  the  other  "violet  left."  Furthermore,  in 
order  to  compare  personal  errors  of  measurement,  two  ol)Mr\ers 
could  conveniently  measure  together,  one  at  eat  h  eyepiece,  viewing 
each  other's  settings  or  making  alternate  settings.  (Sui  h  a  nuthocj 
of  comparison  between  two  observers  should  pro\e  vaiuabie  in  such 
obscrvaticms  as  the  transits  of  stars,  occultations,  etc)  To 
facilita'  such  comparisons  in  the  measurements  of  spectra,  the 
comparator  should  be  made  to  rotate  and  should  be  set  up  on  a 
narrow  table  with  a  seat  on  each  side.  To  avoid  the  interference 
of  reflections  from  the  outside  surfaces,  the  silvered  surface  shi)uld 
lie  between  two  wedges  or  rectangular  prisms  of  glass. 


220 


AM/./'//  /;.  nii  i.i  KV 


I'or  ;irran>;rnunl  li  ihi'  ll.irlmann  ^jki  tru-omiparator  may 
l)r  lasily  adajjlnl  liy  nmuvinn  the  usual  mImt  ma>k  ht'twtin  the 
Kimpoiunts  if  the  doublf-prism  jjlarni  IkIow  the  t'yq)ii'ci'.  half- 
silvi-rinn  thi-  laic  til  one  of  iho  i)risins,  ami  cTnientinK  the  i)risms 
toUitluT  anaiii  with  Canada  l:alsani.  With  this  diviir  the  Harl- 
mann  toniparator  pussfSMs  all  the  advantages  it  ordinarily  has. 
and  in  addition  the  followinj;: 

I.  One  doul)le-i)rism  sulVues  for  all  eomparisons.  In  the 
llartniann  .iistrunient  various  kinds  of  masks  are  made  between 

r 

V- 


I.  New  Form  of  S|iti  tro-romiiamlor 


II,   Adapti'il  Ilartmann  SiMjclro- 
ii>m|xinitor 
K.  i-yi'l.icfc;  //.V.  half  silvered  surfaii-,  (I.  nhji-itivcs;  T.  pholoKraphii  |.l.itrs 


the  romiionents  of  the  double-prisms,  to  make  possible  the  com- 
parison of  si>ectra  of  <litTerent  configurations;  and  it  is  also  neces- 
sary to  focus  both  images  at  this  mask  in  .)r(ler  to  have  the  edges  of 
the  latter  shaqi.  If  the  center  of  the  mask  be  in  focus,  the  outer 
edges  are  out  of  focus  (as  Ilartmann  pointed  out),  and  this  has  a 
disturbing  elTect  on  the  observer.  Furthermore,  a  vertical  line  at 
this  surface  is  in  focus  only  at  its  middle  and  can  therefore  not  be 
used  for  setting  on  spectrum  lines  in  the  ordinary  way.  These 
(lilViculties  are  all  overcome  by  using  the  half-silvered  surface.  In 
this  case  the  images  may  bo  brought  to  focus  beyond  the  double- 
prism  where  masks  of  aii>    'esired  configuration  may  be  emi)loye<l, 

'  /.rihi  liriil  fur  hi.slninicnlatktinjc.  31.  .'05   207,  ii)0<i;  also  Astrophyskal  Journal, 
H,  .'S.s.  I  OCX). 


.1   .VAII'  FORM  Oh  sri'i  I  K<U<>\ir\K\n>K 


ai) 


;in<l  whiTf  ;nlju>l,il>U'  spiilir  linrs  may  lie  u^til  when  ih^ind. 
Thus  «(ini|)arisi(ii>  ami  liiu'  lii>f»  linii^  jna\  In-  niaili-  al  llu-  -.iww 
tinif. 

J.  When  till-  half  silvirrd  surl'an'  i--  u-i<l.  i'  i>  |tu>-iMr  In  plan' 
thi'  inuiKis  in  mimidtinc  in  onirr  to  iK'tci  t  ilitl\rtn>rs, 

1,.  'I'hf  tii-w  (Icvici-  makes  piKsihlr  thf  fnii>li>ymf?it  nl'  the  uuu 
j)arator  lor  nua>urin^'  phntoj;ra|>hs  ol  >ptitra  !>>  Ihf  |iromi-ini; 
iiH'tho*!  su^jm'stril  l)y  I'AiTslifil,  nanu'ly,  lliat  i>l  ii->iiiu'.  willi  tin- 
ni-jjatiM-  to  Ik-  nii'asviri'tl,  a  ]>o^ilivi-  platr  niaili-  I'roin  il.  aiui 
placfd  n-viTsi'd  to  iif^jativo  ind  loniul.'  I  l\a\f  a(!apl4.|  tin  li  irl 
niaim  comparator  for  this  i>urpoM-  and  lia\c  fou  i  i'  \ir\  sali^- 
factory.  It  ovi-rmmi's  thi-  disadvaiitajii-  oi  iln-  nu  ilif  'Acr^hrd 
has  c'mj)loyi'd  of  slidiiii;  p<isiii\f  al»ov»' iu)i,i  iiilha*  '.the   niw 

mt'thiMl  thi-  rdms  of  positive  and  m'nati\'    nia>   Im-  i      i-.   I  ■'       'u- 
sami   plant'.     Clhr  dilVitiilty  of  having  iiu-  lllnis  n    i  in  i 
foriis  has  hi'i'H  ]>ra(  tic  ally  oviTttmic  l>y  lAfrsht<i  hy  r  !ii|.!... 
ohjfi  live  of  loim  foiiis.  1      'i'ht   new  inrlhod  pu-^.SM-i  ar     w;  'd 

advanla,  •  in  that  the  intensity  or  ii>h>r  of  the  luam-.  ot  !ii  ■ 
positive  and  negative  may  !>»■  a'tered  independ('iitl\     ihti- 
it  possible,  by  malihinj;  the  ii\ttii>itits  of  the  llo^ili\l  and  l 
or  by  increasing  the  contract,  to  measure  the  di^planmi- 
spe(  tral  lines  of  almost  any  charat  ter.  ism  the  broal  !ine-  in 
stellar  s])ectra. 

4.  Hy  o\erlapi)inj;  the  spectra  no  parts  of  them  need  !« 
out,  as  is  the  c,i>e  in  usinj;  the  arbitrary  ma>ks  of  tlu'  Harti-i m 
instrument. 

In  Tabic  I  are  jjiven  the  means  of  the  mea>uremenls  of  dis- 
placements fpHKluced  meihanically)  of  15  lines  i\X4ii)')  ^oi) 
42()i  .0^0,  intensities  i  5),  of  six  exposures  of  the  spei  trum  of  the 
solar  limb  by:  (i)  the  ordinary  methcKl  of  bi>,eitin^'  with  sjiider 
line,  takinjj  the  dilTereiues  between  means  of  four  settin^'>  on  tlu' 
middle  strip  and  means  of  twu  >cltin;,'s  on  eath  of  t\vo  out>iile 
strips  of  spectrum,  each  way  (violet  rit;ht  and  \  iolet  left)';  I."  by 
measuriuf^  ne^iative  (\iolet  left)  with  positive  of  itself  (\iolet 
right)  on  the  adapted  Ilartmann  compar.itor.  takitv.^  dilTeriiices 

■  KoJjikitna! Oh<.endtory  liullflin.  No.  ;:,  km  j. 

'  Juiirn.il  Kii\\il  A\lro>uimU'it  Sodely  of  ('■JK.i</.j,  5,  .(i).S,  i<)i  i. 


iai 


R.xu'ii  i:  ni:  ury 


Ik  twicn  iiuans  of  two  Mttin>;s»)n  thi*  mi<l<lli'  strip  ami  means  of  two 
srttin^'s  oil  each  of  the  two  outsidr  stri|)s  of  s|MHlruni,  i-ath  way 
(violit  lift  ami  viulit  rinhn.  A  lonipan'sun  of  thi-  rcsuiis  of  the 
two  iiuthtHls  shows  the  prartirahiiity  of  the  new  (lt\ict'  and  the 
lesseninK  (nearly  halving)  of  the  prohahle  error  of  setting  obtained 
l)y  employing;  the  |)ositive-with  iiej^ative  methiHl. 

TAHI.K  ; 
Ml  vsi  KKMK.vrs  i)F  I'lxTK   I.701    BY    Twil  MiriKll.-l 


I.     ItisFi  rioN  WITH  st'irtft.K  Line,  igii 


Mian  (li>i>lacfnirnl  in  mm 
I'rohalilf  rrror,  >\nf,\i:  line. 
I'rolialiU'  frror  i>f  mean 


'O  o<>qo 

O    OO.'C) 

o  oooS 


Mran  lisplaccment  in  mm 
I'rtihaMi-  crmr,  sintle  line. 
I'robalilf  I'rror  i>f  mi-an 


iMcani 


o  o<i<)g'o  070.' o  lyMjo'o  o<>go  o  0^)860  o(>u4 
o  00,(0  0  oo.'7  0  ooi7jo  001510  ooj()  o  ooJ() 
o  000.H  o  0007  o  0007  o  ooo4'o  ooof<  o  0007 

II.      IVlsiriVR-WITII  .Nfci'.4TI\E.  Igl7 


I  Mraiu 


t  I  i  ; 

O   0(lQ.2  O  0700'0   07080   07040   Ohc;00   l3tH)!0  o(H^ 

o  oojoo  00140  00150  00120  00150  00140  0015 
o  ooo5|C  0004.0  000(0  ooo.vo  00040  00040  0004 


When  the  ailapled  Hartniann  lomparator  is  used,  rcmeasure- 
nients  of  solar  rotation  plates  show  j;ood  agreement  with  my  earlier 
measures  by  the  method  of  bisection  of  lines;  and  the  comparisons 
promise  to  throw  light  on  the  systematic  ditTerences  in  the  measure- 
nunts  «)f  the  same  lines  on  the  same  plates  by  ililfercnl  observers. 
For  example,  the  measurements  <>f  ig  lines,  X  5506. o<)5  5688  4.56, 
Plate  1.845(1),  iire: 
Bisirlion  of  lines  hy  spiJir  thread: 

1)l'  Lury,  mean  of  <)  measures.  loi  i-  igi6.  is         1  618  km/si-c. 

I'lasketl,  iiu'aii  of  j  nifa>uri's.  nji  1,  is 1   605  km/sec. 

I'osithc  "uithniHiilhc: 

KviTshid,  I  im-asup.'.  1016.  is i   6,^6  km  sec. 

Df  l,ur>'.  iiuaii  of  5  measuas,  igi;,  is i  610  km  sec. 

I'o  test  the  a|>plicability  of  the  new  form  of  comparator  to  the 
determination  of  stellar  radial  velocities.  I  have  measured  plates  of 
^  (leminorum  with  positives  of  solar  standard  plates  (or  vice  versa), 


.1   .VAir  nRM  OF  .S /'/•;(  TWO  (()»//■  I  M /OAT 


ii.^ 


I 


st'lt'ttinR  plates  whirh  had  hiiii  pri'viously  iiuaMirtd'   itiy  J.  S 

I'laskftl)  in  testing  the  llartnutnn  s|HTtr(>-n>mparat«)r.     In>tiai. 

groups  i)|  ioiupariM>n  liiu-i  ami  >{roups  of  stiilar  ami  •«i|.ir  lims 

Ininf;  aii>!ru-<l  in  turn,  as  in  the  Hartniann  nutlioil,  thi-c  ^mups 

are  brought  into  onncideme  in  turn,  positive  littinj;  into  negative 

in  a  most  satisfying  manner.     In  all  ( .i«.es  tw<>  s«•tti!J^^  were  made 

tin  solar  and  stellar  eoineidenies;  and  one  on  eai  h  of  the  two  strips 

of  comparison  sjH'itrum  at  eaih  rejjion.      I'he  plates  were  then 

reversetl  and  measured  in  the  same  way.     I.ess  than  .t  minute  at 

i\uh    region   each   way   was   the   avera;'      time   expended       The 

•asurements  arc  given  in  table  If.  and  .ne  degree  of  reliability  of 

e  measures  may  bo  judged  by  the  following  measurements  of  a 

zero  displaiement  (22  regions)  of  solar  standard  14(12  with  positive 

plates  A  and  H  from  it: 

1462  with  jKisitivc  \,  — o  0010  mm 

1462  with  positive  B, —o  0007  mm;  o  0000  mm;  o  ooiOmm;o  0004  nmi 

Mean,  o  00006  mm;  or  o  04  km  see. 

Probable  error  of  single  measure,    *o  24  km  sec;  proljable  errir  •  l" 

mean,  *o  14  km  sec. 

(It  is  to  be  expected  that  the  errors  can  be  lessened  considerably 
by  adopting  Kvcrshed's  methtnl  of  using  negative  violet  left  and 
positive  violet  right,  or  vice  versa,  even  though  the  measurement  is 
in  this  case  confmed  to  u  single  comparison  line  ami  a  single  sohir 
and  stellar  line  a  meth<Mi  which  has  the  obvious  advantage  (f 
yieUling  information  concerning  the  ochavior  of  the  individual 
lines.) 

Fr(mi  Table  II  it  will  be  seen  that  repiated  measurement >  are 
close  in  the  case  of  Plates  1527  positive  .\  and  1520  negative,  and 
much  closer  for  1527  negative  and  1520  positive  .\.  For  the 
former  the  probable  error  of  a  single  measure  is  =*=o  4^  km  ^ec; 
and  for  the  mean.  ±0.22  km  sec;  while  for  the  latter  the  jirob- 
able  error  of  a  single  measure  is  o  07  km  sec;  and  for  the  mean. 

0  0.5  km  sec.     This  latter  is  a  degree  of  accuracy  seldom  attained, 

1  believe,  for  stellar  plates  of  the  low  dispersion  use<l,  by  either  the 
bisection  metho<l  or  the  Hartmann  method  for  so  few  settings  and 

'  Rtport  of  the  Chief  AAronomer,  ii)0<>,  pp.  iHj  f. 


224 


RALPH  E.  l)F.  LIRY 


ri-Kions.  Accuracy  of  settinj,'  is  (IqR'ndfnt  to  ;i  ^rfat  doKrce  on 
the  cartful  bahinciii),'  of  the  intensities  of  positive  and  ne^jativc 
when  making  the  settings  or  when  printing  out  the  positive.  The 
agreement  between  the  overlajjping-positive-wit h-negative  measure- 
ments (De  Lury)  and  the  ah'gning-negative-with-negative  meas- 
urements il'Iaskett)  is  only  fair;  and  both  measures  seem  greatly 
superior  to  the  agreement  of  tl,i-  solar  standards  or  of  the  stellar 
plates. 

T.VBI.i;  II 

.Mk.xsikkmknt.s  ok  f*  (;k.\ii\iiki  M  iiv  Two  Mk.thods 

(I)f  I.ury  usiiiK  i.<)>itivc  with  ncKalivo;    I'laskftt  usins  the  Hartniann  molhml. 

ne(?alive-with-ncgative.) 


M  C.KW.  I'urt 

I 
Sin  I'laik 

\o.  OF 

I)  (Dr.  LiRv. 

.Measured  knluiH 
\flmity    Vclotily 
km,  set",    km,  sec. 

<JI7) 

.Mean 

\ei«K"i!y 
km  set. 

P(Pl 

Measure*: 
\elui  ily 
km  set. 

ASKr.rr, 

Reiluted 
\eloiily 

km  set, 

2  .  h(i 
2    JJ 

90«) 

Mean 
Velmity 
km,  sec. 

1     "      "     " 

Uirnsii- 

ENtK 
I'-l) 

km.  set-. 

1.(73-.  ... 
'373- 

'3f'o-(-A 
14O2+A 
I4"2-|-Ii 

14'>2  +  C' 

l520  +  .\ 

i5-'o-|-A 

'S-'o+A 

'S^o-I-A 

1520  — 

1520- 

1520- 

1520- 

'.S20  +  A 

15  20+ A 
1520-l-A 
i52o-(-A 

20 

22 

II 
1  I 
II 
II 

1  I 
1  I 
I  1 
II 

II 

24.80 
24.88 
25.01 
24  84 
23 .  74 
23  30 
23  Q4 
31.12 

20.  IS 

27.12 

2.i   "0 
20  31 
20.13 
26.09 
26. 12 

2.88 
3.0S 
3  ii 
3  04 
1. 84 
1.40 
2  04 
1.88 

0  85 

'44 
2  41 

'   05 
I.OO 

1  42 

'38 

1. 41 

2,88 
3" 

24.7.S 
24.  25 

J   SO 

—  0.02 

1373- 

.2431        2    51 

'373-    .  ■ 

■!  47 

-0  64 

'373- 
'373- 

-5    01      ;     3.  I  I 

'373-       . 

I   70 
I   88 

311 
2   03 

+  1.35 
+O.IS 

'472-.  ... 

'.i27  +  A.. 

3' .27 
-'7  03 

2    03 

-'32 

i5-'7+A  . 

1.S27+A... 

■  ,S-'7+A... 

"44 

1527- 

1527- .  .  .  . 

1527- 

'5^7-.... 

'■45   ' 

2    32 
2.50 

-f-o  87 

2 .22  ' 

+0.34 

The  main  advantages  of  the  new  form    of  comparator   are: 

r.  A  minimum  of  ojjtical  .surfaces  are  used. 

2.  Images  may  be  brought  into  coincidence;  and  thus  the 
Kvershed  positive-with-negative  method  of  measuring  spectra 
may  be  emi)loye<l  without  the  disadvantages  found  in  using  the 
positive  over  the  negative  and  with  the  added  advantage  that  the 
intensities  of  positive  and  negative  may  be  altered  independently 
and  contrast  gained  by  using  colored  filters. 


.1  \F\y  FOKU  (>/•  .sva  /A-ocou/MA"  lyo/v' 


^.  Twosi'ls  of  iniajifs  an-  ])r<Mlurf<i  ;inii  may  he  ohsirM-il  in  two 
(lilTtTcnt  (.'yi'pieccs.  the  instrunu'iil  iHiiii;  in  I'.ut  .i  <loiil>lr  lum- 
pariitor. 

4.  In  iniMsurinn  s]>eitr;i.  the  instrunu-nt  ni.iy  hi'  uxil  in  the 
ordinary  way  of  hisi'itinf;  ihi'  lines  with  a  spider  thread;  or  it  may 
he  used  as  a  comparator  for  overhippin^  t)r  alijinin^;.  for  \vhiit\ 
masks  for  various  eonli>;uration  may  l)e  readily  interi  han;;ed 

SoLAK  I'hvsk  s  Division 

Ddmimon  {)iiskr\  xroRV.  Ottauv 

April  mi; 


